两轮机器人在坡面上的运动平衡控制

两轮机器人在坡面上运动时,由于受到重力作用的影响,其姿态平衡控制变得更加复杂。为实现机器人在坡面上的平衡控制,首先建立了两轮机器人在坡面上的动力学模型,然后针对两轮机器人设计一种非线性PD控制器。与传统的线性PD控制器进行仿真实验对比,实验结果说明:在响应速度、稳定性、鲁棒性方面,非线性PD控制有着更好的效果。最后,在姿态平衡控制中加入速度控制,构成双环的PD控制,实现了两轮机器人在坡面上的静态平衡。     

柔性双轮平衡机器人的动力学建模与分析

提出了一种柔性双轮平衡机器人,其机身具有以一段弹簧作为弹性阻尼的被动俯仰旋转关节．运用拉 格朗日方法建立了此机器人在平面运动的动力学模型．基于此模型,首先证明了柔性双轮平衡机器人在直立平衡点 不稳定和局部可控．其次,分析了关节刚度对线性二次型最优姿态平衡控制系统的影响．结果显示,关节刚度减小 在理论上能够加强系统的鲁棒性,却使得控制系统动态性能下降．本文提出的模型及相关分析为柔性双轮平衡机器 人的设计和控制提供了一定理论依据．     

基于Hopfield 网络的柔性两轮自平衡机器人控制

用弹簧模仿人的腰椎,采用LQR 成功实现了机器人实物控制．针对柔性两轮自平衡机器人的姿态控 制,提出了一种基于联想学习的离散Hopfield 网络实现方法,以生物学习控制方式实现柔性两轮自平衡机器人在姿 态控制上的自适应、自组织能力．针对非线性、强耦合的柔性机器人系统,首先定义了合理的能量变化函数,并运用 柔性机器人动力学方程设计了满足该动态过程的Hopfield 网络控制器,然后分析了该控制器的收敛性．仿真实验表 明了该方法的有效性和系统的稳定性．对实验结果进行详细分析,表明了系统姿态控制器设计的合理性和有效性．     

两轮机器人具有内发动机机制的感知运动系统的建立

针对两轮机器人运动平衡控制问题,为其建立起一种人工感知运动系统TWR-SMS（Two-wheeled robot sensorimotor system）,使机器人在与环境的接触过程中可以通过学习自主掌握运动平衡技能.感知运动系统的认知系统以学习自动机为数学模型,引入好奇心和取向性概念,设计了能够主动探索环境以及主动学习环境的内发动机机制.实验结果证明内发动机机制的引入不仅提高了机器人的自学习和自组织特性,同时能够有效避免小概率事件的发生,稳定性较高.与传统线性二次型调节器（Linear quadratic regulator,LQR）控制方法的对比实验表明系统具有更好的鲁棒性.     

两轮自平衡机器人动力学建模及其平衡控制*

针对高阶次、不稳定、多变量、非线性、强耦合的两轮自平衡移动机器人系统,采用Lagrange方程推导出动力学模型,对其进行稳定性和可控性判断,并利用LQR和龙伯格极点配置的方法在此模型的基础上对两轮自平衡机器人的姿态和速度进行控制,可获得较为稳定的动态平衡过程。给出了数学模型推导的具体步骤,分别采用以上两种方法进行了仿真研究和比较。仿真实验结果表明,这两种控制方法对机器人的稳定性控制都是有效的。其中龙伯格极点配置控制方法使系统的跟踪速度更快、稳定性更高,具有较高的实际应用价值。     

基于整形器的两轴柔性航天器自适应姿态控制

针对非线性柔性航天器大角度姿态机动问题,为了抑制在高速运动中产生的振动,提出了一种整形参考轨迹和自适应滑模姿态跟踪控制方法.跟踪过程中所使用的期望姿态角是由最优任意时延(Optimal Arbitrary Time-delay,OAT)输入整形器整形所得参考指令作用于参考模型得到,利用该期望姿态角能够得到更好地跟踪和抑制振动效果.针对非线性柔性航天器参数的未知时变特性和欠驱动特性,设计的自适应滑模控制器不仅能够完成期望的姿态角跟踪,同时还能够有效抑制姿态机动过程中的振动,并应用于单轴非线性柔性航天器的大角度姿态控制系统,并进行了仿真验证.结果表明,所提出的方法是可行而有效的.     

两轮自平衡机器人速度跟踪研究

两轮自平衡机器人系统是一个高阶次,不稳定,非线性,多变量,强耦合的系统.系统采用Lagrange方程进行动力学建模,将神经网络自组织算法应用于此模型,并对两轮机器人的平衡和速度进行控制,其难点是对车体速度和车轮速度的控制.本文采用神经网络自组织算法,使输出准确地跟踪输入,使机器人按照指定的移动速度和转动速度运动.将该算法与OBS算法相比较,仿真实验结果表明,自组织算法使系统的跟踪速度更快,具有较高的实用价值.     

云模型控制器在两轮自平衡机器人中的应用

两轮自平衡机器人控制系统具有高阶次、多变量、非线性且强耦合的特性,因此难以建立精准的数学模型。针对两轮自平衡机器人系统的复杂性,对其平衡控制系统进行了研究,提出了一维云模型控制器的设计方法。运用该方法,成功地实现了两轮自平衡机器人的平衡控制,并比较了一维云模型控制器在三规则和五规则下对系统性能的影响。试验结果表明:一维云模型控制器在两轮自平衡机器人平衡控制系统中具有良好的控制性能和强抗干扰性,五规则控制器具有更加优越的控制效果。云模型控制器成功应用在两轮自平衡机器人平衡系统中,并在试验样机平台体现了良好的平衡性能,为今后云模型控制器的设计提供参考,也推进了云模型控制器在硬件平台实现的进程。     

两轮自平衡机器人的自适应模糊平衡控制

在两轮自平衡机器人系统的平衡控制中,为解决因所建立的数学模型不准确和存在未知干扰而影响控制性能的问题,设计了一种自适应模糊控制方法.首先,运用牛顿力学法建立了系统在斜坡上运动的数学模型.针对所建动态模型的非线性,提出采用单点模糊化、乘积推理机和中心平均解模糊化的方法构建了自适应模糊逻辑控制器,然后通过李雅普诺夫稳定性分析的方法,导出控制器的自适应律.在MA TLAB/Simulink中,对自适应模糊控制的两轮自平衡机器人的平衡情况进行了仿真,结果表明,提出的自适应模糊控制器可以实现系统平衡,并具有自适应能力和鲁棒性,为两轮机器人优化控制提供了依据.     

两轮自平衡机器人惯性传感器滤波问题的研究

针对惯性传感器在两轮机器人姿态检测中存在随机漂移误差的问题,基于卡尔曼滤波实现对倾角仪与陀螺仪的信息融合,设计了简单而实用的滤波算法,对传感器的误差进行补偿后得到机器人姿态信号的最优估计,从而将其应用于两轮自平衡机器人系统。实验结果表明,采用卡尔曼信息融合的方法,来得到机器人姿态信息最优估计是有效可行的,并且有利于机器人完成自平衡的控制。     

Development of minimalist bipedal walking robot with flexible ankle and split-mass balancing systems

This paper presents a novel design of minimalist bipedal walking robot with flexible ankle and split-mass balancing systems.The proposed approach implements a novel strategy to achieve stable bipedal walk by decoupling the walking motion control from the sideway balancing control.This strategy allows the walking controller to execute the walking task independently while the sideway balancing controller continuously maintains the balance of the robot.The hip-mass carry approach and selected stages of walk implemented in the control strategy can minimize the efect of major hip mass of the robot on the stability of its walk.In addition,the developed smooth joint trajectory planning eliminates the impacts of feet during the landing.In this paper,the new design of mechanism for locomotion systems and balancing systems are introduced.An additional degree of freedom introduced at the ankle joint increases the sensitivity of the system and response time to the sideway disturbances.The efectiveness of the proposed strategy is experimentally tested on a bipedal robot prototype.The experimental results provide evidence that the proposed strategy is feasible and advantageous.     

A momentum-based balance controller for humanoid robots on non-level and non-stationary ground

Recent research suggests the importance of controlling rotational dynamics of a humanoid robot in balance maintenance and gait. In this paper, we present a novel balance strategy that controls both linear and angular momentum of the robot. The controller’s objective is defined in terms of the desired momenta, allowing intuitive control of the balancing behavior of the robot. By directly determining the ground reaction force (GRF) and the center of pressure (CoP) at each support foot to realize the desired momenta, this strategy can deal with non-level and non-stationary grounds, as well as different frictional properties at each foot-ground contact. When the robot cannot realize the desired values of linear and angular momenta simultaneously, the controller attributes higher priority to linear momentum at the cost of compromising angular momentum. This creates a large rotation of the upper body, reminiscent of the balancing behavior of humans. We develop a computationally efficient method to optimize GRFs and CoPs at individual foot by sequentially solving two small-scale constrained linear least-squares problems. The balance strategy is demonstrated on a simulated humanoid robot under experiments such as recovery from unknown external pushes and balancing on non-level and moving supports.     

立方体机器人自抗扰平衡控制方法

针对立方体机器人动力学模型多变量、强耦合的问题,提出一种基于自抗扰控制的平衡控制器设计方法.引入虚拟控制量,并在控制量与输出向量之间并行地嵌入多个自抗扰控制器,从而实现对多变量系统的解耦控制,将系统的动态耦合和外部扰动视为各自通道上的自抗扰控制器的总扰动,在为期望姿态安排过渡过程基础上,设计扩张状态观测器对总扰动进行估计并实时补偿.综合采用经验试凑法和带宽法对控制器参数进行整定,对自抗扰控制器系统进行稳定控制、姿态跟踪、抗扰性和鲁棒性实验,并与PID控制系统进行定量对比分析.仿真结果表明,所设计的自抗扰控制器不仅能有效实现立方体机器人的平衡控制,而且较PID控制器具有更好的响应速度、控制精度和强鲁棒性.     

具有多层感知器力矩补偿的机器人自抗扰控制

本文针对机器人系统的控制特性, 提出了一种基于自抗扰控制(ADRC)的关节控制算法, 该算法可以克服 传统控制算法中存在的如系统抗干扰能力弱, 控制性能受限于建模精度, 动态性能与稳态性能难以兼顾, 控制律设 计较为复杂等问题. 针对受控系统特性给出了一套实际控制器的完整设计方法与参数整定方法, 并根据控制性能指 标设计优化函数完成了最优控制参数的优化, 在系统参数辨识的基础上利用多层感知器(MLP)设计了对建模不确 定性的补偿网络. 数值仿真和实验结果均表明该算法能够实现机器人快速稳定的轨迹跟踪, 具有良好的控制精度 与很强的抗干扰能力, 此外该算法不依赖于精确的系统模型, 降低了实际设计和应用的难度, 具有很好的工程应用 价值.     

Design and development of an intelligent controller for a pole-balancing robot

In this paper, an intelligent controller capable of static balancing as well as dynamic balancing of a pole mounted on a motorized robot is designed and developed. The brain of the intelligent controller lies in the Fuzzy Inference System, which receives as its input displacement, velocity and acceleration information. An embedded instrumentation system onboard the robot measures the displacement of the robot and the angle of inclination of the pole from the vertical position. For static balancing, the controller needs to maintain the pole in an upright position while the robot is free to move on a flat surface. For dynamic balancing, the robot needs to balance the pole while performing transitions up and down a ramp. Furthermore, the robot needs to steer itself back to the center to prevent it from falling off the ramp.     

A Highly Accurate Model-Free Motion Control System with a Mamdani Fuzzy Feedback Controller combined with a TSK Fuzzy Feed-forward Controller

In this paper, a new intelligent robot motion control architecture – a highly accurate model-free fuzzy motion control- is proposed in order to achieve improved robot motion accuracy and dynamic performance. Its architecture combines a Mamdani fuzzy proportional (P) and a conventional integral (I) plus derivative (D) controller for the feedback part of the system, and a Takagi-Sugeno-Kang fuzzy controller for the feed-forward, nonlinear part. The fuzzy P + ID controller improves the performance of the nonlinear system, and the TSK fuzzy controller uses a TSK fuzzy inference system based on extended subtractive- clustering method which integrates information on joint angular displacement, velocity and acceleration for torque identification. The advantage of this kind of model-free control is that it uses the information directly from the input/output of the nonlinear system, without any complex robot model computation, in order to decrease the control system’s sensitivity to any dynamical uncertainty. Furthermore, parametric search for clustering parameters in extended subtractive clustering secures the high accuracy of the system identification. Consequently, this proposed model-free fuzzy motion control benefits from the advantages of two kinds of fuzzy system. It not only incorporates flexible design, good performance and simple conception but also ensures precise motion control and great robustness. Comparisons with other intelligent models and results from numerical studies on a 4-bar planar parallel mechanism show the effectiveness and competitiveness of the proposed control.     

On the Robust Nonlinear Motion Position and Force Control of Flexible Joints Robot Manipulators

The design of a robust nonlinear position and force controller for a flexible joints robot manipulator interacting with a rigid environment is presented. The controller is designed using the concept of feedback linearization, sliding mode techniques, and LQE estimation methodologies. It is shown that the nonlinear robot manipulator model is feedback linearizable. A robust performance of the proposed control approach is achieved by accounting for the system parameters uncertainties in the derivation of the nonlinear control law. An upper bound of the error introduced by parametric uncertainties in the system is computed. Then, the feedback linearizing control law is modified by adding a switching action to compensate the errors and to guarantee the achievement of the desired tracking performance. The relationship between the minimum achievable boundary layer thickness and the parametric uncertainties is derived. The proposed controller is tested using an experimental flexible joints robot manipulator, and the results demonstrate its potential benefits in reducing the number of sensors required and the complexity of the design. This is achieved by eliminating the need for nonlinear observers. A robust performance is obtained with minimum control effort by taking into account the effect of system parameter uncertainties and measurement noise.     

Online Balance Controllers for a Hopping and Running Humanoid Robot

This paper describes online balance controllers for running in a humanoid robot and verifies the validity of the proposed controllers via experiments. To realize running in the humanoid robot, the overall control structure is composed of an offline controller and an online controller. The main purpose of the online controller is to maintain dynamic stability while the humanoid robot hops or runs. The online controller is composed of the posture balance control in the sagittal plane, the transient balance control in the frontal plane and the swing ankle pitch compensator in the sagittal plane. The posture balance controller makes the robot maintain balance using an inertial measurement unit sensor in the sagittal plane. The transient balance controller makes the robot keep its balance in the frontal plane using gyros attached to each upper leg. The swing ankle pitch compensator prevents the swing foot from hitting the ground at unexpected times while the robot runs forward. HUBO2 was used for the running experiment. It was designed for the running experiment, and is lighter and more powerful than the previous walking robot platform, HUBO. With the proposed controllers, HUBO2 ran forward stably at a maximum speed of 3.24 km/h and this result verified the effectiveness of the proposed algorithm. In addition, in order to show the contribution of the stability, the running performance according to the existence of each controller was described by experiment.     

输入有界的自由漂浮柔性空间机器人轨迹跟踪控制

针对自由漂浮柔性空间机器人轨迹跟踪控制问题, 首先利用拉格朗日和假设模态法建立了动力学模型. 分析系统动力学模型, 综合考虑欠驱动、柔性振动等特点, 将其简化为一种带有柔性振动扰动完全可控的动力学模型; 在此基础上, 考虑控制输入受限, 提出一种自适应状态反馈控制策略. 该策略采用自适应技术实时在线学习柔性振动扰动参数, 从而保证控制律对柔性振动扰动具有良好的鲁棒性; 最后, 基于Lyapunov方法证明了该控制策略能够实现关节期望轨迹的跟踪. 仿真验证了该控制策略对控制输入受限系统轨迹跟踪控制的有效性和可靠性.